Precor Treadmill Troubleshooting Error 15 - DC Bus Over Voltage

Dec 29, 2021

Applies to Treadmills

Issue symptoms

The DC bus (motor) voltage is monitored. When the treadmill is used by a vigorous exerciser walking or running at a steep incline or, when they’re pushing against the handlebars while the belt is moving, the AC(Alternating Current) motor becomes a generator, forcing power back into the motor controller. This excess power would cause the bus voltage to increase enough to damage the control module if not for the dynamic brake resistor DBR(Treadmill Dynamic Break Registor), which automatically switches on to absorb the excess power. Error 15 is an indication that the Bus Voltage exceeded the bus voltage limits, either because the DB(Dynamic Break) system wasn’t functional or because the bus voltage power exceeded the DB system limit.

Troubleshooting steps – all models unless noted

1. Check the error log to determine the error frequency and repeatability.
   1. If a one-time event, clear the error log and return to service.
   2. If repeated occurrences of the error are shown, clear the error log, raise the elevation to 15%, and walk at a fast but comfortable pace, pushing slightly against the handrail. If you can easily generate an Error 15, replace the dynamic brake resistor (DBR).
2. TRM10/Gen06 treads only – Test the MC(Motor Controller) by running on the tread going 7-8 MPH with incline at 0%. Does the error occur within 30 seconds?
   1. If yes, replace the motor controller drive and the dynamic brake resistor (DBR).
   2. If no, proceed to the next steps.
3. Check dynamic brake resistor (DBR) connection.
   1. Switch OFF unit.
   2. Verify all dynamic brake resistor (DBR) connections are connected and seated properly.
4. Check dynamic brake resistance.
   1. Check the dynamic brake resistance. It should be 90 to 110 ohms. If greater than 150ohms, replace the dynamic brake resistor (DBR).
   2. TRM800 only – Check the resistance between either terminal of the switch connector (smaller black) to either terminal of the resistor element connector (larger white/natural). The resistance should be greater than 1Meg of resistance. If less than 1Meg, replace the dynamic brake resistor (DBR).
5. If none of the above, replace the motor controller.